Best materials and service for flat roof?

lndross

We have an urban rowhouse with a flat roof, divided into three sections, about 800 sq. feet total. Each section is a completely separate roof, there is a leak around the drain in one section. The first company said the drain was faulty, but did not mention rotted wood around the sliding doors. Second company said nothing worng with drain, did mention rotting wood around sliding doors. The two bids we are considering:
1st company ($6500-7000):
- tear off the roofing down to roof decks
- replace any deteriorated decking @ $45 per plywood sheet
- install a tapered instulation system and retro fit drain into the existing drains
- apply single ply modified bitumen roof system
- brush on aluminum coat to reflect sun
- install new 24 gauge galvanized perimeter flashings where necessary, will caulk the top of the metal.

2nd company ($4000):
- tear off the roofing
- nail on fiberglass base sheet
- torch down one ply modified bitumen roof system
- brush on aluminum coat to reflect sun

Questions:
- do we do all three sections or just the section that's leaking?
- why is the first company so much more expensive?
- how do we know if there is something wrong with the drain?

send_it_all

Questions:
- do we do all three sections or just the section that's leaking?
- why is the first company so much more expensive?
- how do we know if there is something wrong with the drain?[/quote]

-I would replace all sections

-Why is the 2nd company so cheap? Do they both have licenses?, Insurance? pay workman's comp?...Maybe the 2nd guy hires illegal aliens to do the labor and if they fall off the roof and break their neck, he just buries them in the wilderness (although with the price of gas he might just find a nearby dumpster).

-You get a professional's opinion. If you dont believe it...get a couple more.

Ed the Roofer

The first company is providing a much better solution to the problems always associated with low slope or flat roofs. The tapered insulation will promote better drainage to the low spots. Standing water on a low slope asphaltic roofing material is the surest way to void any potential warranty liability.

Also, the tapered insulation system and the additional required labor to install the pieces to slope correctly is time consuming and costly.

All sections, if they are tied into each other should be done at the same sequence, or else the tie-in for a future roof will not be a new roof, it will just be a patch ocer an existing area.

Also, the 1st company is providing a specification for an architectural sheet metal flashing, but it should be more definitive as to where precisely it is going to be deemed "necessary".

Ed

lndross

Thanks so much for the quick reply and great advice. Everything makes sense. Two other things...
- The sections are completely independent of each other; would you still do all three at once?
- main worry about first company (now that you've explained the higher cost) is that they didn't mention anything about rotted wood around sliding door frame where it is now obvious that water is coming in (pocket of water near frame). An understandable oversight, or a reason to question their expertise?

AaronB

is the sliding door part of tghe roof? Will the leaky area be part of the tear off project?

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lndross

The sliding door leads out of a sunroom that is in between the two sections of roof (and the roof over the sunroom is the third section of roof). So you exit the sliding door and step out onto the rooftop that has the leak, which had a deck on it that we just removed. The rotting wood is all around the sliding door, and there is a pocket of water in the roof at one side of the door. Yes, the leaky area will be part of the tear off, but the first company didn't say anything about the door frame itself. One of the companies - a third, actually -focused on the rotting wood as the biggest problem. We're not going with this third company because they used rolled roofing, but they one of two companies that mentioned the rotting wood.

Ed the Roofer

You possibly need to discuss the specific areas of rotting wood and how it will be handled by the contractor you intend to choose.

It may or may not be an oversight. Some tasks are too unknown as to how long they will take to correct and therefor get limped into the time plus materials category of the contract specifications. If the entire door needs to be removed, the roofing contractor may or may not have the proper technical expertice to do so confidentally, so that could be understandable. The better option is to also have them or yourself contract with a window door replacement contractor as an additional scope of work.

Ed